This invention relates generally to plastic, integrally molded security fasteners which are passed through apertures in adjacent panels or elements to join the elements together. More particularly, the invention relates to a tamper-indicating security fastener that provides a tell-tale sign that someone has attempted to breach the security of the panels or elements, such as a tote box and cover, that were intended to be held together by the fastener.
The instant security fastener is well suited to secure the cover to the container of a tote box assembly. Tote boxes are commonly used for delivery of sundry goods from a manufacturer, wholesaler or distributor, etc. to a supermarket, variety store, department store, or the like. The tote box assemblies, such as those shown in U.S. Pat. Nos. 3,360,162 and 3,379,341, have apertures formed in the cover and the container, and, when these apertures are aligned, security fasteners are snapped into the apertures to lock the cover to the container. The secured box deters pilferage, retains the merchandise within the box during shipment, and yet can readily be unlocked, when needed.
Several types of security fasteners have been, and presently are, used with existing tote box assemblies. One security fastener that has enjoyed considerable commercial acceptance is disclosed in U.S. Pat. No. 3,779,374, granted Dec. 18, 1973 to Kenneth R. Bockenstette. The fastener (22) shown in such patent is a plastic structure having a pair of locking parts (28) connected to the free end of the shank (26) of the fastener and the head (24) of the fastener, respectively. The locking parts include perpendicularly disposed locking surfaces (36) and inclined cam surfaces (50) leading thereto from the free end of the shank part. During the fastener inserting operation, the cam surfaces are operable to flex the locking parts with both (1) a torsional movement, and (2) an inward bending movement.
Another security fastener, which is executed in plastic, is described in U.S. Pat. No. 4,312,614, granted Jan. 26, 1982 to John P. Palmer et al. Such fastener includes inner and outer members (1,2) interconnected by flexible straps, or struts (30). The manner in which this fastener functions is shown in FIGS. 2a-2e of the Palmer et al. patent, and the fastener is utilized specifically with a tote box in FIG. 9.
While the above described security fasteners performed satisfactorily under most conditions, certain drawbacks were encountered. For example, the fastener disclosed by Palmer et al. was relatively complex and the tolerances would be difficult to maintain when molding such fasteners by conventional mass production techniques. The fastener disclosed by Bockenstette requires a special tool for insertion, and the cost and inconvenience of using a special tool limit the appeal of such fastener.